70 lines
1.9 KiB
Zig
70 lines
1.9 KiB
Zig
const std = @import("std");
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const io = std.io;
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const mem = std.mem;
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const os = std.os;
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const warn = std.debug.warn;
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const allocator = std.debug.global_allocator;
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pub fn main() -> %void {
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var args_it = os.args();
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const exe = try unwrapArg(??args_it.next(allocator));
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var catted_anything = false;
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var stdout_file = try io.getStdOut();
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while (args_it.next(allocator)) |arg_or_err| {
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const arg = try unwrapArg(arg_or_err);
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if (mem.eql(u8, arg, "-")) {
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catted_anything = true;
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var stdin_file = try io.getStdIn();
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try cat_file(&stdout_file, &stdin_file);
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} else if (arg[0] == '-') {
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return usage(exe);
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} else {
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var file = io.File.openRead(arg, null) catch |err| {
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warn("Unable to open file: {}\n", @errorName(err));
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return err;
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};
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defer file.close();
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catted_anything = true;
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try cat_file(&stdout_file, &file);
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}
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}
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if (!catted_anything) {
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var stdin_file = try io.getStdIn();
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try cat_file(&stdout_file, &stdin_file);
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}
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}
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fn usage(exe: []const u8) -> %void {
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warn("Usage: {} [FILE]...\n", exe);
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return error.Invalid;
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}
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fn cat_file(stdout: &io.File, file: &io.File) -> %void {
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var buf: [1024 * 4]u8 = undefined;
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while (true) {
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const bytes_read = file.read(buf[0..]) catch |err| {
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warn("Unable to read from stream: {}\n", @errorName(err));
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return err;
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};
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if (bytes_read == 0) {
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break;
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}
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stdout.write(buf[0..bytes_read]) catch |err| {
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warn("Unable to write to stdout: {}\n", @errorName(err));
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return err;
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};
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}
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}
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fn unwrapArg(arg: %[]u8) -> %[]u8 {
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return arg catch |err| {
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warn("Unable to parse command line: {}\n", err);
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return err;
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};
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}
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